When your toenail turns black, you might wonder what's happening and whether you should be worried. Not only is the discoloration an eyesore, but it can also be painful.
That's why we spoke to Nelya Lobkova, DPM, a New York City-based podiatrist at Step Up Footcare, who shares the most common causes of this condition, plus how you can restore your toenails to tip-top shape.
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What Causes a Black Toenail?
1. Trauma to the Nail
Most commonly, a black toenail signals a subungual hematoma, or blood pooling under the nail due to an acute or repetitive trauma, Dr. Lobkova says. As far as acute injury, think: dropping something heavy on your foot or stubbing a toe.
In terms of repetitive damage, even a seemingly benign activity like running regularly can result in bruising and blackening of a toenail. That's because trauma to the toenail can occur from the toe rubbing against the top of the shoe or slamming into the end of it.
2. Too-Tight Shoes
Speaking of shoes, wearing ones that are too tight can also put pressure on — and break — the blood vessels in the toes, leading to blood leakage under the toenail, according to the American Osteopathic College of Dermatology.
3. Infection or Disease
In other cases, a black toenail could indicate a fungal infection under the toenail or, much less commonly, a melanoma (a type of skin cancer) in the toenail, Dr. Lobkova says.
How to Treat a Black Toenail
If a subungual hematoma is the source of your black toenail, here are a few tactics you can take to help it heal properly.
1. Avoid Shoes That Compress the Toenail
If there's pain or pressure in the affected toenail, the best footwear to sport is a sandal or an open-toed shoe, Dr. Lobkova says.
However, if you don't have any discomfort (and/or less than 75 percent of the toenail is black), you can wear whichever shoes feel good on your feet and engage in physical activities as usual, she says.
2. Trim the Toenail Regularly
"The impacted toenail should be trimmed in the normal fashion," Dr. Lobkova says. "If it gets too long, this may cause the nail to lift or fall off."
3. Be Patient
If the toenail doesn't need to be drained (more on this later), there's nothing you can do to speed up the natural healing process, which involves the body absorbing the bruise and the toenail reattaching seamlessly to the healthy nailbed, Dr. Lobkova says.
"Keep in mind, it takes eight months to one year for a full new nail to grow," she adds.
When You Should See a Doctor
"When more than 75 percent of the nail is black or blue, or there is tenderness on compression or a pressure sensation," it's time to see a podiatrist, Dr. Lobkova says.
If indeed it's a blood blister under the hard part of the toenail, your podiatrist may have to evacuate or drain it, Dr. Lobkova says. "Do not attempt this on your own because you can potentially damage the nailbed beneath the blister," she cautions.
Once the painful blood blister is drained, you'll feel fast relief. To enhance your recovery, your podiatrist may advise you to soak the nail in Epsom salt to ward off a bacterial infection, Dr. Lobkova says.
In addition, you should also see your doctor if you notice visible changes in the black toenail within a month (for example, the discoloration appears to be moving down toward the base of the nail), because this may indicate fungal disease or possibly melanoma, Dr. Lobkova adds.
Is this an emergency? If you are experiencing serious medical symptoms, please see the National Library of Medicine’s list of signs you need emergency medical attention or call 911.